<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<ul>
    <li>
        <p>hello</p>
        <span>world</span>
        </li>
    <li>
        <p>hello</p>
        <span>world</span>
        </li>
    <li>
        <p>hello</p>
        <span>world</span>
        </li>
        <ol>
            <li>
                <ol>
                    <li>苹果</li>
                    <li>苹果</li>
                    <li>苹果</li>
                    <li>苹果</li>
                </ol>
                </li>
        </ol>
</ul>
</body>
</html>
    <script src="js/jquery-3.2.1.js"></script>
    <script>
        $(function () {
            $("ul > li").css("color","blue");
            $("ul").children("li").css("fontSize","40px")
        })
    </script>